Canadian health officials have added heart health warnings to the safety labels on the antidepressant drug Lexapro (sold in Canada as Cipralex).

According to a release from Health Canada has issued a statement this week notifying the public of its intent to update the safety information included with Lexapro to note its “dose-related risk of abnormal heart rhythm.” Lexapro is part of the controversial and widely-prescribed class of antidepressant drugs, selective serotonin reuptake inhibitor (SSRI) drugs.

Based on the results of a clinical trial of Lexapro, patients taking the drug were more likely to suffer from an electrical charge problem in their heart known as QT prolongation. This can cause an abnormal heart rhythm that can be life-threatening to patients taking the drug. Health Canada will update the safety labels of its Cipralex but there is no update from the domestic Food and Drug Administration on new warnings for U.S. patients.

The agency has made the following specific warnings on the drug labels for Lexapro:

“Cipralex should not be used in patients with a heart condition known as congenital long QT syndrome, or in patients with QT interval prolongation.”

“Use of Cipralex is discouraged in patients who are also taking drugs that prolong QT interval or that decrease electrolyte levels in the body.” Health Canada notes that some of the drugs include those to treat heart rhythm, antipsychotics and opioid painkillers.

The agency also established a maximum dose of 10mg daily for patients over 65 years old, those with liver problems, or those taking the heartburn drugs omeprazole or cimetidine.